Atherosclerosis and coronary artery disease affect a large number of people in the United States, and is a leading cause of death. Intravascular ultrasound (IVUS) has begun to make a significant impact in diagnosis and treatment of these conditions. It has been used in lesion visualization, stent placement and stent monitoring, and has advantages over other modalities in that it is capable of distinguishing various tissue types. A number of visualization methods such as elastography and RF analysis have advanced IVUS, though these require a large bandwidth transducer. Many existing transducers do not have adequate performance, and require acoustic mirrors or are not directed in a way that provides the most clinical significance. In Phase I, TRS Technologies and Penn State University developed a micromachining method to create composite piezoelectrics using single crystals. This PMN-PT material has a very high electromechanical coupling coefficient (k33 > 90%) which provides ultrasound transducers with an inherently wide bandwidth. In the Phase I program, a single element transducer was constructed that exhibited 80% bandwidth with one acoustic matching layer, which is significantly higher than current commercial IVUS transducers. For the Phase II program, TRS proposes to build on these results by constructing an IVUS segmented annular array with broad bandwidth for use in interventional cardiology. This device would provide a three dimensional representation of the arteries, and a forward looking architecture. In the program, the array transducer will be modeled, fabricated and evaluated using in vivo animal studies. [unreadable] [unreadable] [unreadable]